Chris:  I think that Country Homes Campers in San Jose installs
a poptop like you've described.  Whether this is procured from
Sportsmobile or not, I don't know, but you could try phoning them..

/martha rubin
nrubin@s1.csuhayward.edu
'79 bug 'vert (white)
'81 westy (puke eggnog {ivory})